1. Field of the Invention
This invention relates generally to computer memory, and more particularly to a system and method for recapturing dedicated peripheral device memory, thereby making this memory available for general use by the computer system.
2. Description of the Background Art
Many peripheral devices, such as video displays or graphic accelerators, require random access memory (RAM) to operate. To improve system performance and peripheral device functionality, computer designers typically provide dedicated peripheral RAM for these peripheral devices. This dedicated RAM is generally accessible only by the peripheral device and is not available or reassignable to other system components such as the central processing unit (CPU). However, it is not uncommon for a peripheral device to use only a portion of its dedicated peripheral memory, thereby wasting valuable RAM capacity. For example, a typical desktop computer system has four megabytes of Dynamic RAM (DRAM), or similar RAM such as VRAM, dedicated to the video controller and display. Yet, when displaying about 800 by 600 pixels at eight bits per pixel for color definition alone, the typical high resolution SVGA video monitor uses only about one megabyte of its dedicated memory. Thus, three megabytes of RAM remain unused. Laptop computers require even less dedicated memory due to the physical limitations of liquid crystal displays.
This problem is exacerbated when system designers implement wide databuses for coarse grain information transfer between a peripheral device and the dedicated peripheral memory. To obtain this wide databus and thereby improve system performance, many system designers use several memory chips in parallel, which incidentally provides more memory greater than needed by the peripheral device. With increasing RAM requirements, systems should not squander such valuable resources. Therefore, a system and method are needed to make more efficient use of peripheral device dedicated memory.